Basically, it is about a pair of dudes who work in a bookstore. But they are really professional avengers. As in, they punish the wicked on behalf of people who are too weak to do so themselves. I can only remember two story arcs. #1. Rapist/Murderer who got released from prison The mom of the dead kid went to the avengers and they killed the rapist for her. #2. Bullying at school A kid killed himself after getting bullied at school. There's a teacher who turned a blind eye. The avengers were hired for the case and they tortured the bullies and gouged out the teacher's eyes. So any of you know what manga this is?
This isn't what you're looking for, but a professional Avenger who is near John Wick grade would be the guy from Dendrobates. Instead of a pair in a bookstore, he's a cop from the accounting division who looks into cases that can't be solved because of laws and corruption and finds the victims to 'hire' him before hunting down the worse of humanity or just plain jackasses. It's not what you're looking for though. I'm sorry. Closest thing I know about.
I've definitely read something like that. I dunno about the name but I think that it went into hiatus.
Oh, I know Dendrobates but the manga I have in mind isn't it. They work as a team. And one of them runs a bookstore. The other is his partner.